asp.net c# Change style for all rows inside a datalist on condition

I do not have the right answer, sorry. Not sure there is one, though

ok now you got the answer for your question right ?

Sorry Jignesh, I mislead you. Each txt1, txt2...txt21 has a value, actually is a sum of the column but it's not important for my case. What I want to do is to color green the div that has a value less than 5.

With

DataRowView drv = (DataRowView)(e.Item.DataItem);
int rating = int.Parse(drv.Row["U1"].ToString());

if (rating > 0)
{
    TextBox txt = (TextBox)e.Item.FindControl("txt1");

    txt.Attributes.Add("style", "background-color: Green;color:white;font-size:9px");

}

I get the value for each div and apply style. I was hoping for a way to check all divs (txt1, txt2,...txt21), one by one and apply style for those meeting the criteria

protected void DataList2_ItemDataBound(object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        for (int i =1; i <=5; i++)
        {
            // Dynamically get the control name like txt1, txt2, txt3
            string controlId = $"txt{i}";
           

            // Find the control
            TextBox txt = (TextBox)e.Item.FindControl(controlId);

            if (txt != null && i <= 5)
            {
                // Apply the style to the control
                txt.Attributes.Add("style", "background-color: Green; color: white; font-size: 9px");
            }
        }
    }
}

Thank you Jignesh for your answer, what I need is to check the value for each txt1..21 box and if is between 0 and 5 to have a color. 

I tried your code buy having

protected void DataList2_ItemDataBound(object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        for (int i = 1; i <= 9; i++)
        {
            // Dynamically get the control name like txt1, txt2, txt3
            string controlId = $"txt{i}";
            int r = int.Parse(controlId.ToString());

            // Find the control
            TextBox txt = (TextBox)e.Item.FindControl(controlId);

            if (txt != null && r < 5)
            {
                // Apply the style to the control
                txt.Attributes.Add("style", "background-color: Green; color: white; font-size: 9px");
            }
        }
    }
}

but I get the error "Input string was not in a correct format."

Hello Marius,

If your text box name starts with txt... then you can find the below,

protected void DataList2_ItemDataBound(object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DataRowView drv = (DataRowView)(e.Item.DataItem);
        int rating = int.Parse(drv.Row["A1"].ToString());

        if (rating > 0 && rating < 5)
        {
            for (int i = 1; i <= 20; i++)
            {
                // Dynamically get the control name like txt1, txt2, txt3
                string controlId = $"txt{i}";
                
                // Find the control
                TextBox txt = (TextBox)e.Item.FindControl(controlId);

                if (txt != null)
                {
                    // Apply the style to the control
                    txt.Attributes.Add("style", "background-color: Green; color: white; font-size: 9px");
                }
            }
        }
    }
}